/* Copyright (c) 2008, The Visigoth Software Society
 * Copyright (c) 2006, Sun Microsystems Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright notices,
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name Visigoth Software Society, FreeCC, Sun Microsystems, Inc. 
 *       nor the names of any contributors may be used to endorse or promote 
 *       products derived from this software without specific prior written 
 *       permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.visigoths.freecc.lexgen;

import java.util.*;

import org.visigoths.freecc.Grammar;



/**
 * Describes regular expressions which are choices from
 * from among included regular expressions.
 */

public class RChoice extends RegularExpression {
  
  public RChoice(Grammar grammar) {
    super(grammar);
  }

  /**
   * The list of choices of this regular expression.
   */
  public List<RegularExpression> choices = new ArrayList<RegularExpression>();

  Nfa GenerateNfa(LexicalState lexState, boolean ignoreCase)
  {
     CompressCharLists();

     if (choices.size() == 1)
        return choices.get(0).GenerateNfa(lexState, ignoreCase);

     Nfa retVal = new Nfa(lexState);
     NfaState startState = retVal.start;
     NfaState finalState = retVal.end;

     for (int i = 0; i < choices.size(); i++)
     {
        Nfa nfa;
        RegularExpression curRE = choices.get(i);

        nfa = curRE.GenerateNfa(lexState, ignoreCase);

        startState.addMove(nfa.start);
        nfa.end.addMove(finalState);
     }

     return retVal;
  }

  void CompressCharLists()
  {
     CompressChoices(); // Unroll nested choices
     RegularExpression curRE;
     RCharacterList curCharList = null;

     for (int i = 0; i < choices.size(); i++)
     {
        curRE = choices.get(i);

        while (curRE instanceof RJustName)
           curRE = ((RJustName)curRE).regexpr;

        if (curRE instanceof RStringLiteral &&
            ((RStringLiteral)curRE).image.length() == 1)
           choices.set(i, curRE = new RCharacterList(grammar,
                      ((RStringLiteral)curRE).image.charAt(0)));

        if (curRE instanceof RCharacterList)
        {
           if (((RCharacterList)curRE).negated_list)
              ((RCharacterList)curRE).RemoveNegation();

           List<Object> tmp = ((RCharacterList)curRE).descriptors;

           if (curCharList == null)
              choices.set(i, curRE = curCharList =
                                    new RCharacterList(grammar));
           else
              choices.remove(i--);

           for (int j = tmp.size(); j-- > 0;)
              curCharList.descriptors.add(tmp.get(j));
         }

     }
  }

  void CompressChoices()
  {
     RegularExpression curRE;

     for (int i = 0; i < choices.size(); i++)
     {
        curRE = choices.get(i);

        while (curRE instanceof RJustName)
           curRE = ((RJustName)curRE).regexpr;

        if (curRE instanceof RChoice)
        {
           choices.remove(i--);
           for (int j = ((RChoice)curRE).choices.size(); j-- > 0;)
              choices.add(((RChoice)curRE).choices.get(j));
        }
     }
  }

  public void CheckUnmatchability()
  {
     int numStrings = 0;

     for (RegularExpression curRE : choices) {
        if (!(curRE).isPrivate() &&
            //curRE instanceof RJustName &&
            curRE.getOrdinal() > 0 && curRE.getOrdinal() < getOrdinal() &&
            curRE.getLexicalState() == this.getLexicalState())
        {
              grammar.addWarning(this, "Regular Expression choice : " +
                 curRE.getLabel() + " can never be matched as : " + getLabel());
        }

        if (!curRE.isPrivate() && curRE instanceof RStringLiteral)
           numStrings++;
     }
  }

}
